Emory and Piedmont hospitals have filed lawsuits to prevent Gwinnett Medical Center from starting to perform open-heart surgeries at its Lawrenceville, GA, facility. The lawsuits aim to reverse a state approval of Gwinnett's open-heart program by the commissioner of the state Department of Community Health.

One big suburban cardiology practice has been snapped up by a hospital system and another is on the block, deals likely to deliver a defibrillator-like jolt to Chicago's lucrative heart-care market. Midwest...